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Viktor [21]
3 years ago
15

Q 16.1: Select the first step in the Wittig reaction. A : The alkyltriphenylphosphonium halide is deprotonated by a base to make

a phosphorus ylide. B : The phosphorus ylide reacts with the aldehyde or ketone to make an oxaphosphetane. C : Triphenylphosphine attacks the alkyl halide to produce an alkyltriphenylphosphonium halide. D : The oxaphosphetane decomposes to form the alkene and triphenylphosphine oxide.
Chemistry
1 answer:
Dennis_Churaev [7]3 years ago
6 0

Answer:

The phosphorus ylide reacts with the aldehyde or ketone to make an oxaphosphetane.

Explanation:

The Wittig reaction is a reaction that occurs between a phosphorus ylide and an aldehyde or ketone. The final products are an alkene and triphenyl phosphine oxide.

The first step in the reaction is the attack of the phosphorus ylide on the aldehyde or ketone. This is followed by attack of oxygen on phosphorus to form a [2+2] cycloaddition product (oxaphosphetane)  which  decomposes to form the alkene and triphenylphosphine oxide.

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Even in pitchblende, polonium is exceedingly rare: 1,000 tons of ore must be treated to yield 40 milligrams of polonium. It has a one-part-in-ten-thousandth-thousandth-thousandth-thousandth-thousandth-thousandth It is found in nature as a byproduct of the radioactive decay of uranium, thorium, and actinium.

Atomic Number: 210

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3 years ago
Consider the following reactions. (Note: (s) = solid, () = liquid, and (g) = gas.)
White raven [17]

Answer:

Both are endothermic reactions.

Explanation:

Chemical equation:

1/2H₂(g) + 1/2I₂(g)  →  HI(g)  + 6.2 kcal/mol

Chemical equation:

21.0 kcal/mol + C(s) + 2S(s)  → CS₂

Both reaction are endothermic because heat is added in both of reactions.

Endothermic reactions:

The type of reactions in which energy is absorbed are called endothermic reactions.

In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.

For example:

C + H₂O   →  CO  + H₂

ΔH = +131 kj/mol

it can be written as,

C +  H₂O  + 131 kj/mol  →  CO  + H₂

Exothermic reaction:

The type of reactions in which energy is released are called exothermic reactions.

In this type of reaction energy needed to break the bonds are less than the energy released during the bond formation.

For example:

Chemical equation:

C + O₂   →  CO₂

ΔH = -393 Kj/mol

it can be written as,

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6 0
4 years ago
f 65mL of sulfuric acid and 25mL of sodium hydroxide were mixed and the solution had a density of 1.01g/mL, what is the heat of
user100 [1]

The question is incomplete, here is the complete question:

If 65 mL of sulfuric acid and 25 mL of sodium hydroxide were mixed and the solution had a density of 1.01 g/mL, What is the heat of the calorimeter in kJ given the temperature change of the above equation is -5.5 K. You may assume the solution has a heat capacity of 4.180 J/gK. Express your final answer in kJ and with 2 decimal places

<u>Answer:</u> The heat of the calorimeter is 2.09 kJ

<u>Explanation:</u>

To calculate the mass of solution, we use the equation:

\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}

Density of solution = 1.01 g/mL

Volume of solution = [65 + 25] mL = 90 mL

Putting values in above equation, we get:

1.01g/mL=\frac{\text{Mass of solution}}{90mL}\\\\\text{Mass of solution}=(1.01g/mL\times 90mL)=90.9g

To calculate the heat released by the reaction, we use the equation:

q=mc\Delta T

where,

q = heat released

m = mass of solution = 90.9 g

c = heat capacity of solution = 4.180 J/g.K

\Delta T = change in temperature = -5.5 K

Putting values in above equation, we get:

q=90.9g\times 4.180J/g.K\times (-5.5K)=-2089.8J=-2.09kJ

Heat released by the solution will be equal to the heat absorbed by the calorimeter.

<u>Sign convention of heat:</u>

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

Heat absorbed by the calorimeter = -(-2.09) = 2.09 kJ

Hence, the heat of the calorimeter is 2.09 kJ

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As water freezes its molecules move farther apart. As when water freezes , Its move farther apart .

And the cause of this movement is hydrogen bond that is formed among the surrounding water molecules that causes water molecules to move apart. So as water freezes its molecules move farther apart, it is the correct answer .

5 0
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